A STUDY OF LINER/LIFTER WEAR IN CHADORMALU SEMI-AUTOGENOUS MILLS.

Due to certain advantages in (semi-)Autogenous-Ball mill circuits in most of the highthroughput ore grinding units of mineral processing plants, much attention is paid to optimize mill performance. Despite the maturity of the grinding mill mechanical design, the efficiency of the grinding media has previously been ignored. Different liner materials and shapes are used in different situations (in a variety of ore types and operational conditions), but the best economically and operationally chosen for one operation is not the same for the other. In this research, the possibility of establishing a relationship between liner/lifter wear rate and variations in the composition (SiO2% and FeO%) of an iron ore is investigated. The ore belongs to a magmatic high grade iron ore deposit located at Chadormalu mine in the province of Yazd, Iran. A significant change in the mineralogical composition of the ore was observed during the sampling days which resulted in the variation of the feed ore work index . Measurements and determination of liner/lifter wear rates and patterns concluded that the critical liner segments posed too much abrasion during ore grinding. By performing the metallurgical analysis of liner materials and after correlation of wear rate with ore composition, it was concluded that the homogeneity in the metallurgical microstructure of the alloyed steel (such as the uniform distribution and amounts of the constituent phases) has a great influence on the response of the liner/lifter to the variations of ore composition. Magnetite with a greater abrasion index than hematite, also in finer particles, is responsible for additional wear rate (abrasion) in liners , but hematite with greater toughness/grindability (work index) exists in the mill with larger particle sizes, thus it could produce wear on liner parts with less tolerance to impact as is the situation for martensitic steels.